A polyphenylene ether resin is normally formed by blending a polyphenylene ether and a styrene resin in proportions that are dependent on the levels of heat resistance and molding fluidity that are required. The polyphenylene ether resin may be further blended with an elastomer component and additive components such as a flame retardant, an organic filler, and a heat stabilizer as necessary in order to form a polyphenylene ether resin composition.
Polyphenylene ether resins have excellent heat resistance, mechanical properties, molding processability, acid and alkali resistance, dimensional stability, electrical properties, and so forth, and are thus widely used in fields such as consumer electronics, office automation, office equipment, information devices, and automobiles. Among such applications, in the case of cooling fans (propellers) and the like in electric and electronic devices such as consumer electronics, office automation, office equipment, and information devices such as PCs, there has been demand in recent years for extremely high mechanical properties such as heat resistance, flexural strength, and tensile strength in use as a thin molded article, and there has also often been demand for durability in order to enable long-term resistance to stress even under high-temperature conditions. Consequently, there is ongoing investigation of polyphenylene ether resin compositions that contain a large amount of an inorganic filler, and in particular glass fiber.
On the other hand, in recent years it has often been the case in applications such as described above that extremely high levels of flame retardance have been required that have not been conventionally achievable. It is known that in the case of a polyphenylene ether resin composition in which a large amount of an inorganic filler such as glass fiber is blended with a polyphenylene ether resin, flame retardance can be improved to a certain extent by further blending a flame retardant (for example, refer to PTL 1 and 2). However, it also known that since a fibrous inorganic filler has a wick effect, it is extremely difficult to increase the flame retardance of a resin composition containing a large amount of glass fiber to a high level through blending of a flame retardant, and once a certain level of flame retardance is reached, flame retardance cannot be further increased simply by further increasing the amount of the flame retardant (for example, refer to PTL 3).